Drawing circles on electronic devices, such as display devices has not been a straight forward endeavor. Existing circular arc generators consist of a series of chained straight-line vectors (chords) connecting points along a perimeter of the desired circular arc. The higher number of vectors or lines in the arc, the better the fit to the desired curve. Circles with large radius can require hundreds of these vectors to obtain reasonably high fidelity.
This existing approach requires a trade-off between circular arc fidelity and processing/rendering throughput to handle numerous vertices. In general, this tradeoff typically results in a circle and circular arcs which have obvious discontinuities where the chords are clearly visible. Custom solutions embody hardware acceleration of arcs, but existing commercially available graphics chipsets do not have such features. The arcs also tend to be of lower image quality due to the limited line anti-aliasing that is available with most graphics chips.
Textures have been used in other approaches. In one such approach, a trapezoid is used as the texture, drawn within a large rectangle. However, this approach is wasteful in terms of storage, and also requires two-dimensional super sampling. Further approaches have attempted to use a large circular texture drawn within a large quadrilateral. This again requires a large amount of storage to hold the texture.